Why I Walk Around Shirtless…….And You Should Too


Salutations, earthlings!

According to my blog counter it’s been 131 hours since we last talked, and I must admit it’s been a lonely sojourn.

I’m sure you all have lives,  but the innards of my (textbook-clenching) soul can’t find an outlet for my vitamin anxieties, making each one of these posts a uniquely cathartic experience.

Trial-and-error experimentation has taught me that Mom, first dates, the postman, drug store clerks, second dates, customer service telephone reps, Starbucks baristas, third cousins, cocktail waitresses, my personal trainer, last dates, and the guy sitting next to me in my co-working space are not good venues to talk about such things.

I’m an addict.  I have to resist entirely, and if I get even a little taste of a topic like the ideal carrier molecule for folate then BOOM! the words just flow, along with little balls of spittle that come flying out like machine gun shells.


Since we last talked an important change has taken place within me.  Or rather, outside of me.  When I stroll down the Manhattan streets I do so without a shirt, allowing my nylon-carpet chest hair to glisten in the sun and beads of sweat to cake around my hardened nipples.

Based on the reactions I get you might think I’m trying to attract invasive taunts from offended bystanders, but my intentions are much more simple:  I’m loading up on vitamin D.

You Should Load Up On Vitamin D, Too

My methods are a bit risqué, but the reasoning behind my mid-day exhibitionism is rock solid.

Most people don’t get nearly enough vitamin D.

The RDA is way too low for optimal health.

And I’m sorry, but there’s no better way to get it than to walk around buck naked in the afternoon sun.  The more skin (and less clothes), the better.

Clothing and sunscreen are the mortal enemies of healthy vitamin D levels.

If you saturate your skin with UV rays, this is how dressed and undressed people differ in the amount of vitamin D that actually sticks:

If you’re wearing clothes and sunscreen you might as well be holed up in an igloo.

You need bare, unencumbered flesh soaking up those UV rays to make vitamin D.

Not All Sunlight Is Created Equal

Soaking in the sun is the most efficacious way to make vitamin D.  But it’s not guaranteed that your sunlight is worth a damn.

To make vitamin D your skin must be exposed to sunlight that has a UVB irradiation level of at least 20 mg/cm2.

If you live above latitude 40° the sunlight doesn’t have this intensity between the months of November and March.

So if you live in Boston during the winter you could spend all day, everyday flim-flamming outside with your genitals flopping in the wind and still not make a lick of vitamin D. [footnote]This is a mild exaggeration.  Your body would still make some,  just not enough to be healthy.[/footnote]

Not All Body Parts Are Created Equal Either

Some body parts are better than others at making vitamin D.

Your head and shoulders are almost useless.  You could scorch your noggin’ in the LA sun until you got actinic keratosis and still be deficient.  Your arms are a little better, but not by much.

Your chest and legs however, are vitamin D factories.  They’re about 4-5 x more effective in converting 7-DHC to D3 in your body.  That’s right folks, loincloths rule!

No skin really is a sin.  If you want to make vitamin D you have to make it as awkward as possible for your neighbors.

And About That 400 IU RDA…..

The first vitamin D requirements were formulated by looking at people who didn’t have vitamin D deficiency and averaging their blood levels.  That’s dumb.


Our needs for vitamin D evolved when we spent all day outdoors in an equatorial environment.  Under those conditions your body will make 10,000 – 20,000 IU’s of the vitamin before your skin starts to turn pink from UV radiation.  That’s 50x the recommended amount.  If you’re white it takes 15 minutes to do this.

As we’ve seen here, your typical daily trek, even if you live in a sunny area, probably won’t suffice since you spend most of it inside and fully clothed.  But those people were still being used to calculate the numbers.

In 1997 the Institute of Medicine declared the desired daily amount of Vitamin D to be 400 IU.  The thinking was that this is the amount that allows infants to have healthy bones.


So what happens when you give that amount to adults?  Practically nothing.  In some cases it could even lead to deficiency.

If you want your body’s vitamin D regulated hormones to be saturated and fully operational you need vitamin D levels of about 80 nmol/L.  That’s the equivalent of about 2,000 IU/day.   Populations that live close to the equator and lifeguards have vitamin D levels that are twice this amount and don’t experience adverse side effects.

In clinical trials people can dose with 5,000 to 10,000 IU and they seem to be just fine.

Clothing:  An Oppressive Institution Whose Time Has Passed

Since the Emmanuel Church shooting there’s a lot of talk in the media about society’s collective need to face the issue of racism:

Well, let me take this moment to be an apostle for another agent of oppression:

Why must we be shackled by the social bonds that punish us unless we overdress?

The typical person has a pseudo-deficiency in vitamin D, with circulating 25(OH)D levels of about 25 µg/L, well below the amount necessary for fully active PTH levels or optimum calcium absorption.

Vitamin D regulates over 3,000 genes and has a role in the pathology of every major lifestyle disease.   Yet we turn our backs on the only way our bodies were meant to make it.

People, we can do better!

Okay, I’m kidding.

I don’t really want to campaign for clothing justice.

But think about losing that shirt……


1).  Webb, A. R., et. al. “Influence of Season and Latitude on the Cutaneous Synthesis of Vitamin D3: Exposure to Winter Sunlight in Boston and Edmonton Will Not Promote Vitamin D3Synthesis in Human Skin” http://press.endocrine.org/doi/abs/10.1210/jcem-67-2-373

2).  Matsuoka, LY, “Use of topical sunscreen for the evaluation of regional synthesis of vitamin D3” http://www.ncbi.nlm.nih.gov/pubmed/2161436?dopt=Abstract

3).  Matsuoka, LY, “In vivo threshold for cutaneous synthesis of vitamin D3.” http://www.ncbi.nlm.nih.gov/pubmed/2549141?dopt=Abstract

4).  Haddock, L, et. al. “25(OH)D serum levels in the normal Puerto Rican population and in subjects with tropical sprue and parathyroid disease.”

5).  Institute of Medicine. “Dietary Reference Intakes: Calcium, Phosphorus, Magnesium, Vitamin D, Fluoride”  http://www.nap.edu/openbook.php?record_id=5776

6).  M Lehtonen-Veromaa, et. al. “Vitamin D intake is low and hypovitaminosis D common in healthy 9- to 15-year-old Finnish girls” http://www.nature.com/ejcn/journal/v53/n9/abs/1600844a.html

7).  Heaney, R, et. al. “Calcium Absorption Varies within the Reference Range for Serum 25-Hydroxyvitamin D” http://www.tandfonline.com/doi/abs/10.1080/07315724.2003.10719287

8).  Haddock, L.  “25(OH)D serum levels in the normal Puerto Rican population and in subjects with tropical sprue and parathyroid disease”

9).  Heaney, R.P., et. al “Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol” http://ajcn.nutrition.org/content/77/1/204.abstract?ijkey=c8455d6859ca5ea48d526f1e19a4c4c4977027e8&keytype2=tf_ipsecsha

3 thoughts on “Why I Walk Around Shirtless…….And You Should Too”

    1. Amy,

      Not really. Vitamin D is a commodity ingredient and can be purchased from a variety of places. Which one you choose doesn’t really matter.


  1. The elderly and obese need especially high levels of vitamin D. The former don’t make it in their skin (more than 70% less than normal people) and the latter store too much of it in their fat cells.


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